Regeneration of ruthenium hydride complex isomerization catalysts

ABSTRACT

Ruthenium hydride complexes containing tertiary phosphine, arsine or stibine ligands which are useful as catalysts for isomerization of olefins are effectively regenerated by contact with hydrogen.

United States Patent Pennella Apr. 15, 1975 REGENERATION OF RUTHENIUM [56] References Cited HYDRIDE COMPLEX ISOMERIZATION UNITED STATES PATENTS CATALYSTS 3,488,400 1/1970 Candlin et a1. 212/431 P 75 Inventor: Filippo p n Bartlesville O l 3,538,133 11/1970 Knoth 260/429 R 3,793,257 2/1974 Pennella et a1. 260/683.2 [73] Assignee: Phillips Petroleum Company,

Bartlesvllle O Primary Examiner-Arthur P. Demers 22 Filed; Oct 2 1973 Attorney, Agent, or FirmNeuman, Williams,

Anderson & Olson [21] Appl. No.: 409,810

[57] ABSTRACT [52] 252/411 R; 252/431 P; 260/429 R; Ruthenium hydride complexes containing tertiary 269/6832 phosphine, arsine or stibine ligands which are useful as [51] Int. Cl B0l 11/02 catalysts for isomerization of olefins are ff ti l [58] Field of Search 252/411 R, 431 P; generated b ct with hydrogen.

4 Claims, N0 Drawings REGENERATION OF RUTHENIUM HYDRIDE COMPLEX ISOMERIZATION CATALYSTS This invention relates to regeneration and maintenance of activity of ruthenium hydride complexes containing tertiary phosphine, arsine or stibine ligands which are useful isomerization catalysts.

BACKGROUND OF THE INVENTION The copending application Ser. No. 194,698 filed Nov. 1, 1971, now U.S. Pat. No. 3,793,257. discloses and claims the invention wherein the double bond of an isomerizable olefin reactant is shifted by contact with a ruthenium hydride complex containing tertiary phosphine. arsine or stibine ligands.

The ruthenium hydride complex employed according to that invention can be represented by the formula (R3Q)3RUH2Z wherein each Q is independently selected from phosphorus, arsenic, and antimony; Z is selected from H N or NH and wherein each R is independently selected from organic radicals containing up to 20 carbon atoms. Preferably the organic radical is free of active hydrogen atoms and reactive unsaturation. Preferred R groups are alkyl, cycloalkyl and aryl hydrocarbyl radicals and mixtures thereof, such as alkaryl, aralkyl, alkcycloalkyl. with each R group containing up to carbon atoms.

Some examples of suitable ruthenium complexes are: (triphenylphosphine RuH (triethylphosphine RuH N- [(4-methylphenyl );;phosphine l RuH (NH;,). (phenyldimethylphosphine) -RuH,, (diphenylmethylphosphine)=;RuH (N (dimethyllaurylarsine);iRuH- (NH (trimethylarsine)3RuH,. (tribenzylarsine )3RUH2( N (tricyclohexylarsine )3. RuH (NH;,). (trieicosylarsine)3-RuH (triphenyl stibine):iRuH (N I(4-methylcyclohexyl) phosphine ];,RuH NH (tridecylstibine);;Rul-l [(4-fluorophenyl) -phosphine];,RuH (N [(4-chlorophenyl) phosphine];,RuH (NH (trioctylstibine) RuH (triisobutylstibine);;RuH (N (triphenylphosphinel-gb triphenylarsine)RuH (NH (triphenylphosphineh. RuH (N and the like and combinations thereof.

The ruthenium hydride complexes can be prepared by any convenient method known in the art. Generally convenient methods are illustrated in the Journal of the American Chemical Society (JACS) 90, 7172 (1968) and Journal of the American Chemical Society 92, 301 l (1970). An example of a convenient method is the reaction of a suitable ruthenium compound with an alkali metal borohydride in the presence of an alcohol, such as the reaction resulting from an admixture of dichlorotris(triphenylphosphine)ruthenium and sodium borohyride in methanol to yield tetrahydridetris(triphenylphosphine )ruthenium.

The ruthenium dinitrogen and ammonia complexes can be prepared conveniently by the addition of nitrogen or ammonia directly to a (R Q) RuH, complex. A general procedure is provided by Journal of the American Chemical Society 90, 7172 (1968) and Journal of the American Chemical Society 92, 3001-3016 1970).

The ruthenium complexes employed are air-sensitive and are generally unstable in the presence of air or oxygen-containing atmospheres. Accordingly, the preparation and use thereof should exclude or appreciably restrict air or oxygen, as well as exclude any reactive substance or atmospheres which tend to reduce the effectiveness of the complex in an isomerization process.

In general, the ruthenium complexes have limited solubility in commercially important olefin isomerization process feedstocks. Advantageously, in some cases, therefore, the complex is employed in the presence of substantially inert solvents to facilitate mixing of olefin reactant and ruthenium catalyst. Representative inert organic solvents which can be used include aromatic hydrocarbons including benzene, toluene, ortho-xylene, meta-xylene, para-xylene, as well as other inert solvents including tetrahydrofuran and similar solvents.

The ruthenium complexes can be employed in heterogeneous catalystic olefin isomerization reactions by depositing the complex on a solid inorganic oxide catalyst support. Such support materials are commonly known as refractory oxides and include synthetic materials as well as acid treated clays or the crystalline aluminosilicates known in the art as molecular sieves. Synthetic refractory oxides are preferred. Exemplary synthetic refractory oxides include silica, alumina, silicaalumina, silica-magnesia, boria-alumina. silicaalumina-zirconia, and silica-titania-zirconia Preferably. the support, prior to contact with the complex. is dried by calcining. Such a supported catalyst preferably contains from about 1 to about 10 weight percent ruthenium complex based on the weight of support.

Any isomerizable olefin can be employed, including acyclic monoenes and acyclic polyenes embracing dienes, trienes. conjugated diolefins, nonconjugated diolefins. mixtures thereof and the like. The olefins can contain cycloalkyl or aryl substituents or mixtures thereof. Because of their commercial importance, preferred olefins contain from 4 to 20 carbon atoms per molecule. and more preferably from 4 to 10 carbon atoms per molecule. Representative olefins are the following: l-butene, l-pentene. l-hexene, 3-hexene. ldecene, S-methyl-l-hexene, 7-methyl-l-nonene, 5- ethyl-l-octene, Z-butene, Z-pentene. 4-methyl-2- hexene, 4-phenyl-l-butene, 5-cyclopentyl-l-pentene. 4-phenyl-2-butene. 5-isopropyl-2-heptene, Z-decene, 2,3,4-trimethyl-6-dodecene, 1,3-tetradecadiene, 4- eicosene. l-(3-butenyl)-4-ethylbenzene, 1-(3- pentenyl)-3-methylcycloheptene, 1,3-octadiene, 1,4,7- decatriene and the like, and mixtures thereof.

The amount of ruthenium hydride complex employed in the isomerization processes can vary widely. Preferably, an amount of complex is used which affords a reasonable amount of isomerization within a reasonable reaction period of time. In general, ruthenium hydride complexzolefin weight ratios of from about 0.00l to about 10 parts by weight of complex per parts by weight of olefin are suitable to the practice of that invention. Time will be about 0.2 100 hours.

The isomerization processes can be carried out as either a batch or as a continuous process using any conventional apparatus. Depending on the mode of reaction and other conditions, such as reaction temperature, complexzolefin weight ratio and contact time, the process can be carried out at any convenient pressure ranging from subatmospheric to about 2000 psig and more preferably from about 0-2000 psig.

The isomerization reaction temperatures can vary widely. In general, the reaction temperature should be such that the reactants and ruthenium complex composites are stable and do not decompose into undesirable by-products or inactive complex composites. Thus, the isomerization process is generally carried out at a temperature in the range of from about 20 C. to about 70 C. and preferably at a temperature in the range of about C. to about 50 C. Ordinarily, the temperature should not exceed about 80 C., at which temperature decomposition of the complex can begin.

The reaction products canbe separated from the reaction mixture by any method known in the art. Suitable separation techniques include filtration, distillation. decantation, adsorption and the like.

OBJECTS OF THE PRESENT lNVENTlON stored or enhanced while it is being used for isomerizing olefins.

SUMMARY OF THE PRESENT lNVENTlON Rejuvenation of ruthenium hydride isomerization catalysts is accomplished by contacting the catalyst with hydrogen. Contacting the catalysts per se in the absence of an isomerization feed with hydrogen can be done periodically to rejuvenate a spent or partially de activated catalyst. 1n the alternative, hydrogen can be introduced during an isomerization reaction to maintain activity of the isomerization catalyst.

DETAILED DESCRlPTlON OF THE INVENTION With the use of hydrogen, restoration of isomerization activity is achieved by catalysts represented by the formula aQh z wherein Q is independently selected from phosphorus, arsenic and antimony; Z is selected from H N or NH and wherein each R is independently selected from organic radicals containing up to 20 carbon atoms, including alkyl, cycloalkyl and aryl hydrocarbyl radicals and mixtures thereof such as alkaryl, aralkyl and alkcycloalkyl.

minimum so that hydrogenation of the olefin is minimized. Generally, an amount of hydrogen ranging from about 1 to 1000 moles H /mole complex will be employed. Preferably, for regeneration the temperature of the reaction mixture while hydrogen is being added is lowered to a temperature ranging from about 100 C. to about 70 C. and most preferably from about 70 C. to about 30C. These temperatures are sufficiently low to reduce the vapor pressure of the olefin to a level where little is lost in regeneration and with minimum hydrogenation. The pressure at which the hydrogen is introduced for regeneration purposes can vary from subatmospheric to about 1000 psig, and preferably from about 0 to about 100 psig. The regeneration times can vary from about 0.1 minute to about 100 hours,

preferably from about 1 minute to about hours.

Following the hydrogen treatment, the vessel is swept with an inert gas such as argon or helium to remove the hydrogen and the temperature and pressure are adjusted to a favorable level for resumption of isomerization. Optionally, following the hydrogen treatment, the reaction vessel is swept with nitrogen or ammonia to form catalyst complexes based on them and then the vessel is swept with an inert gas to form an isomerization atmosphere.

According to a second embodiment of the invention,

an isomerization catalyst as described above is regenerated in the absence of an olefin isomerization feed. In

this embodiment the catalyst, after being used for isomerization, can be dissolved in any inert organic solvent such as, for example, benzene, toluene, xylene, tetrahydrofuran, etc., and hydrogen bubbled through the solution. The temperature at which this treatment is conducted depends on the solvent and can range from 90 C. to 30 C. at pressures from 0 to 1000 psig and for time periods ranging from 1 minute to 10 hours.

The invention and the advantages thereof are further illustrated by the following specific examples.

EXAMPLE I A solution containing 0.02 gram of (triphenylphosphine) -;RuH (N in 20 milliliters of toluene was added to a closed vessel in an argon atmosphere held at 25 C. To the solution was added 3 milliliters 1 .9 grams) of l-pentene and the mixture was stirred. Periodic sampling of the mixture was made by withdrawing 10 microliters of solution and analyzing it by gas-liquid chromatography. The following results were obtained:

Table I Time n-Pentane l-Pentene Trans2-Pentene Cis-2-Pentene (Minutes) (Mole (Mole "/n) (Mole (Mole l 0.14 62.4 35.4 2.05 22 57.9 38.9 3.18 100 0.28 44.3 48.6 6.74 200 0.21 31.7 57.8 10.3 527 0.26 11.3 70.5 17.9 12 days 0.25 2.2 76.1 21.4

According to one embodiment of the invention, regeneration of the above isomerization catalyst is The results show the catalyst is effectively converting the l-olefin to an internal olefin with the predominant achieved in a continuous or batch process by periodiisomer being the trans form.

cally or continuously adding hydrogen to an inert atmosphere maintained over the isomerization reaction mixture. The amount of hydrogen employed is kept at a At this point 3 additional milliliters of l-pentene was added to the closed vessel and stirring and periodic sampling resumed. The following results were found:

Table II n-Pentane l-Pentene Trans-2 Pentene Cis-2 Pentene Time (Mole "/1) (Mole 71) (Mule 70) (Mole "/1) min. 0.13 51.6 37.4 10.8 94 min. 0.14 51.5 37.6 10.7 17 hours 0.16 51.1 38.0 10.1:

The results show the catalyst to be inactive. R is an organic radical containing up to carbon atoms, EXAMPLE I] which process comprises contacting said catalyst at a The vessel containing the solution from Example 1 temperature in the range of from about 100 C. to

was placed in a dry ice-acetone bath and hydrogen was b t 70 C, ith hyd en, the amount of hydrogen bubbled through the solution for 15 minutes. The solul5 l d b i i h range f about 1 t 1000 tion was then left for more minutes under a hydromoles f hydrogen per l f id catalyst b h gen atmosphefe at 14 p The Pressure was reduced amount of hydrogen being insufficient to cause subto atmosphenc y bleeding Off the hydrogen and the stantial hydrogenation of olefins in contact with said o vessel and 1ts contents brought again to 25 C. Stirring 7 catalyst and sampling were resumed. The following results were obtained: 2. A process in accordance with claim 1 wherein con- Table [II Time n-Pentane l-Pentene Trans-2 Pentcne Cis-2 Pentene (Minutes) (Mole '71) (Mole '71-) (Mole 7(1) (Mole "/n) The results show that regeneration of the catalyst tacting of the said catalyst is done in the presence of an with hydrogen restored its isomerization activity while isomerizable olefin.

not affecting the selectivity. Some hydrogenation is 00- 3. A process for rejuvenating or maintaining activity curring as the increase in pentane shows, but the reacf a ruthenium h d id com l olefin isomerization tion is taking place in a hydrogen atmosphere rather t l h vi th f m l than in a more desirable argon atmosphere. (R;,Q) -;RuH- ,Z

Those modifications and equivalents which fall wherem within the spirit of the invention are to be considered 40 0 f selected from arsemc and antm0ny* a part thereof Z 1s selected from N and Nl-l and R is an organic radlcal contammg up to 20 carbon What is claimed 15: atoms 1. A process for rejuvenating or maintaining activity which process comprises contacting said catalyst with of a ruthenium hydride complex olefin isomerization hydrogen in the absence of an isomerizable olefin. catalyst having the formula 4. A process in accordance with claim 3 wherein connQ):r 2 tacting of the said catalyst is carried out at a temperawherein ture in the range of from about 90 C. to about 30 C.

Q is selected from phosphorus, arsenic and antimony, and at a pressure of about 0 to i000 psig.

Z is selected from H N and NH and 

1. A PROCESS FOR REJUVENATING OR MAINTAINING ACTIVITY OF A RUTHENIUM HYDRIDE COMPLEX OLEFIN ISOMERIZATION CATALYST HAVING THE FORMULA
 2. A process in accordance with claim 1 wherein contacting of the said catalyst is done in the presence of an isomerizable olefin.
 3. A process for rejuvenating or maintaining activity of a ruthenium hydride complex olefin isomerization catalyst having the formula (R3Q)3RuH2Z wherein Q is selected from phosphorus, arsenic and antimony, Z is selected from H2, N2 and NH3, and R is an organic radical containing up to 20 carbon atoms, which comprise contacting said catalyst with hydrogen in the absence of an isomerizable olefin.
 4. A process in accordance with claim 3 wherein contacting of the said catalyst is carried out at a temperature in the range of from about -90* C. to about 30* C. and at a pressure of about 0 to 1000 psig. 